1. Field of the Invention
This invention relates to arterial ablation. By way of non-limiting example the invention may be usable to relieve arterial blockage due to atherosclerosis, for example.
2. Description of the Related Art
Arteries affected by diseases such as atherosclerosis may have increased arterial wall thickness due to deposits of cholesterol and cellular proliferation. This leads to increased arterial wall stiffness and reduced internal diameter, and consequently reduced blood flow though the artery.
Hitherto medical intervention to arterial wall thickening has been endoluminal, that is, from the inside of the vessel, such as catheter based balloon angioplasty, laser angioplasty and atherectomy. Such procedures are relatively complex because the blood supply through the artery must be diverted. In addition, endoluminal intervention necessarily involves injury to the internal layer of the artery wall, the tunica intima. The damaged tunica intima heals by intimal hyperplasia and fibrosis. In a significant number of cases, estimated at 25%, the treated vessel is re-blocked within 6 months.
There is a need for a method and apparatus for increasing the flexibility of an arterial wall thickened by disease, in order to increase blood flow through the artery, which is more effective than known techniques and is less likely to result in re-blockage of the artery.
This invention seeks to allow treatment of arterial wall thickening with less or no damage in the tunica intima, thereby avoiding re-blockage due to hyperplasia of the tunica intima during the healing thereof.
It has been unexpectedly found that ablation of the external layer of the artery wall, the tunica adventitia, optionally in conjunction with part of the middle layer of the arterial wall, the tunica media, is effective for reducing or eliminating arterial wall thickening.
According to an aspect of the invention there is provided a method for reducing the thickness of an arterial wall by ablation of the exterior of the artery wall.
By ablating the exterior layer of the arterial wall the tunica intima and inner layers of the tunica media are protected from damage. Re-blockage cannot thereafter be caused by hyperplasia during healing of the tunica intima. The flexibility of the artery is improved due to the reduced effective wall thickness after ablation thus relieving stenosis and improving blood flow through the artery.
In addition, the procedure may be carried out without diverting the blood flow through the artery.
According to another aspect of the invention there is provided apparatus for relieving arterial blockage comprising:
i) apparatus for surveying the thickness of an arterial wall, and
ii) apparatus for ablating the exterior of the arterial wall to increase the flexibility of the arterial wall.
Further preferred features and advantages of the present invention will become apparent from the following description and accompanying claims.